U.S. patent number 6,248,181 [Application Number 09/252,992] was granted by the patent office on 2001-06-19 for composition and method for hydrophilic treatment of aluminum or aluminum alloy.
This patent grant is currently assigned to Nihon Parkerizing Co., Ltd.. Invention is credited to Hiroki Kojima, Masahiro Motozawa, Tomohiro Osako.
United States Patent |
6,248,181 |
Osako , et al. |
June 19, 2001 |
Composition and method for hydrophilic treatment of aluminum or
aluminum alloy
Abstract
Here are provided a composition for hydrophilic treatment of
aluminum or aluminum alloy which can form film having persistent
corrosion resistance and hydrophilicity and not generating odor,
and a method for hydrophilic treatment. Namely, provided by the
invention are a composition for hydrophilic treatment of aluminum
or an aluminum alloy which comprises (P1) a water-soluble polymer
having as a constitution unit monomer(s) (I) represented by the
formula ##STR1## wherein, R.sup.1 represents a hydrogen atom or a
methyl group, and R.sup.2 and R.sup.3 are the same or different,
and each represent a hydrogen atom, an alkyl group having 1 to 4
carbon atoms, a benzyl group or a hydroxyalkyl group having 2 or 3
carbon atoms, and obtained by homopolymerization or
copolymerization of the monomer(s) (I), (A) a water-soluble
trivalent chromium compound, (B) a water-soluble zirconium compound
or titanium compound, and, if necessary, further water, and wherein
the mutual rate of P1, A and B is such that, based on 100 weight
parts of the solid matter of P1, A is 0.01 to 70 weight parts and B
is 0.001 to 70 weight parts, and a method for hydrophilic treatment
using it.
Inventors: |
Osako; Tomohiro (Tokyo,
JP), Kojima; Hiroki (Tokyo, JP), Motozawa;
Masahiro (Tokyo, JP) |
Assignee: |
Nihon Parkerizing Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
12970542 |
Appl.
No.: |
09/252,992 |
Filed: |
February 19, 1999 |
Foreign Application Priority Data
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Feb 19, 1998 [JP] |
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10-054431 |
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Current U.S.
Class: |
148/247;
106/14.15; 148/251; 148/267; 252/390 |
Current CPC
Class: |
C09D
5/084 (20130101); C23C 22/34 (20130101); C23C
22/68 (20130101); F28F 19/02 (20130101); F28F
21/084 (20130101); C23C 2222/10 (20130101); F28F
2245/02 (20130101) |
Current International
Class: |
C09D
5/08 (20060101); C23C 22/68 (20060101); C23C
22/05 (20060101); C23C 022/48 () |
Field of
Search: |
;148/247,251,267,275
;106/14.15 ;252/390 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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24 52 483 |
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May 1975 |
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DE |
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63-171683 |
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Jul 1988 |
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JP |
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63-171684 |
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Jul 1988 |
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JP |
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63-318496 |
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Dec 1988 |
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JP |
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1-270977 |
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Oct 1989 |
|
JP |
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WO 93/15155 |
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Aug 1993 |
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WO |
|
Primary Examiner: Sheehan; John
Assistant Examiner: Oltmans; Andrew L.
Attorney, Agent or Firm: Nixon & Vanderhye
Claims
What is claimed is:
1. A composition comprising components (P1), (A), (B) and (C) for
hydrophilic treatment of an aluminum or aluminum alloy wherein:
(P1) a water-soluble polymer obtained by a polymerization process
selected from the group consisting of:
(i) homopolymerizing a monomer (I) represented by the formula:
##STR7##
wherein R.sup.1 represents a hydrogen atom or a methyl group and
R.sup.2 and R.sup.3 are the same or different, and each represent a
hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a benzyl
group or a hydroxyalkyl group having 2 or 3 carbon atoms,
(ii) copolymerizing two or more of monomers (I),
(iii) copolymerizing at least one monomer (I) with another monomer
(II) copolymerizable with the monomer (I) or salt(s) of the
monomer(s) (II) to provide a ratio of monomer (I) in the total
monomers of 40% by mol or more, and
(iv) subjecting the homopolymer or copolymer resulting from
polymerization (i), (ii) or (iii) to a modification process
selected from the group consisting of
(1) converting amido groups to carboxyl groups by hydrolysis,
(2) converting amido groups to amino groups by a Hofmann
rearrangement,
(3) converting amido groups to --CONH--CH.sub.2
--N(R.sup.4)(R.sup.5) by a Mannich reaction using
HN(R.sup.4)(R.sup.5) and formaldehyde
wherein R.sup.4 and R.sup.5 are the same or different, and each
represents an alkyl group having 1 to 4 carbon atoms, a
hydroxyalkyl group having 2 or 3 carbon atoms or a benzyl
group,
(4) introducing a --CONH--R.sup.6 --NH.sub.2 group by reacting side
chain ester groups with alkylenediamine (H.sub.2 N--R.sup.6
--NH.sub.2) wherein R.sup.6 represents an alkylene group having 2
to 6 carbon atoms, and
(5) converting the amino or substituted amino groups resulting from
reactions (2) to (4) to quaternary ammonium through alkylation,
(A) a water-soluble trivalent chromium compound;
(B) a water-soluble zirconium compound or titanium compound;
and
(C) water;
provided that the ratio of (P1), (A) and (B) is such that, based on
100 weight parts of the solids of (P1), (A) is 0.01 to 70 weight
parts and (B) is 0.001 to 70 weight parts and provided the
composition is substantially completely free of a hexavalent
chromium compound.
2. The composition according to claim 1 wherein monomer (I) is
selected from the group consisting of acrylamide, methacrylamide,
N-methlacrylamide and N,N-dimethylacrylamide.
3. The composition according to claim 1, which further contains a
second water-soluble polymer (P2) in an amount of 1 to 400 weight
parts based on 100 weight parts of (P1) in solid weight basis,
wherein (P2) a water-soluble polymer obtained by
homopolymerization of a monomer (III) or a salt thereof having in
each molecule a carboxyl group, a sulfonic acid group, a phosphonic
acid group, a primary amino group, a secondary amino group, a
tertiary amino group, a quaternary ammonium group, a hydroxyl
group, a glycidyl group or an amido group, provided that monomer
(III) is different from monomer (I),
copolymerization of two or more of monomers (III) and salts
thereof, or copolymerization of monomers (III) or salts thereof
with a nonioic monomer copolymerizable with the monomer (III) or
salts thereof provided it has neither a hydroxyl group, a glycidyl
group nor an amido group,
wherein the ratio of monomer (III) or salts thereof to the total
monomers in polymer (P2) is 40% by mol or more.
4. A composition according to claim 3 wherein the nonioic monomer
copolymerizable with the monomer (III) or salts thereof is selected
from the group consisting of styrene, alkyl (C=1 to 8)
(meth)acrylate and vinyl acetate.
5. The composition according to claim 1 which further contains an
antibacterial agent having a decomposition temperature of
100.degree. C. or more.
6. The composition according to claim 3 which further contains an
antibacterial agent having a decomposition temperature of
100.degree. C. or more.
7. The composition according to claim 1, wherein the water-soluble
polymer is the one obtained by copolymerizing monomer (I) with
monomer (II), and monomer (II) is selected from the group
consisting of 2-hydroxyalkyl (C=2 or 3) (meth)acrylate,
diacetoneacrylamide, N-methylolacrylamide, acryloylmorpholine,
acrylonitrile, alkyl (C=1 to 6)(meth)acrylate, styrene, vinyl
acetate, a monomer represented by the formula: ##STR8##
wherin R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.1 represents one of the following groups: ##STR9##
wherein R.sup.a and R.sup.b are the same or different, and each
represents a hydrogen atom, an alkyl group having 1 to 6 carbon
atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a phenyl
group or a benzyl group, and y represents an integer of 1 to 3,
a monomer represented by the formula ##STR10##
wherein R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.2 represents one of the following groups: ##STR11##
maleic anhydride and itaconic acid.
8. The composition according to claim 3 wherein the monomer (III)
is selected from the group consisting of a monomer represented by
the formula: ##STR12##
wherein R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.2 represents one of the following groups: ##STR13##
maleic anhydride and itaconic acid,
a monomer represented by the formula: ##STR14##
wherein R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.1 represents one of the following groups: ##STR15##
wherein R.sup.a and R.sup.b are the same or different, and each
represents a hydrogen atom, an alkyl group having 1 to 6 carbon
atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a phenyl
group or a benzyl group, and y represents an integer of 1 to 3, and
2-hydroxyalkyl (C=2 or 3) (meth)acrylate, N-methylolacrylamide and
diacetoneacrylamide.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a composition for hydrophilic treatment
of aluminum or aluminum alloy and a method for hydrophilic
treatment using it. More detailedly, this invention relates to a
composition for hydrophilic treatment for giving excellent
hydrophilicity, deodorant properties and corrosion resistance over
a long period to aluminum or aluminum alloy, more detailedly
aluminum or aluminum alloy materials, aluminum or aluminum alloy
products, for example aluminum or aluminum alloy-made heat
exchangers, etc., and a method for hydrophilic treatment of
aluminum or aluminum alloy using the composition.
2. Statement of Related Art
Heretofore, many of aluminum or aluminum alloy-made heat exchangers
are designed so that the areas of the heat-radiating parts and the
cooling parts can be as large as possible so as to heighten heat
radiation or cooling effect, and therefor, the intervals among the
fins are extremely narrow. Further, notches called louvres are made
among the fins so as to make draft resistance as small as
possible.
Thus, when such a heat exchanger is used for cooling, moisture in
the air aggregates on the surface of the heat exchanger,
particularly among the fins, the aggregated water is liable to be
water droplets in proportion as the hydrophobicity of the fin
surface increases, and the water droplets often cause clogging at
the fin gaps to increase draft resistance and lower heat exchange
rate.
Further, the water droplets which collected at the fin gaps tend to
scatter by the blower of the heat exchanger, and it often occurs
that the pan installed at the lower part of the heat exchanger
cannot receive all the scattered water droplets and the
neighborhood of the heat exchanger is soiled with water.
Therefore, in order to prevent water droplets from remaining at the
fin gaps and causing clogging, some treatments for giving
hydrophilicity to the surface of the aluminum or the alloy thereof
and enhancing water wettability have been proposed and put into
practice.
Heretofore, agents for hydrophilic treatment applied on the fin
surfaces of aluminum or aluminum alloy-made heat exchangers are
roughly classified into two kinds, namely those wherein organic
macromolecules are bound or added to inorganic compounds,
especially alkali silicates, and those composed of organic
macromolecules alone. The former ones have better hydrophilicity
and hydrophilicity persistency than the latter ones, and are more
often used on the market. However in recent years, the problem of
offensive odor generated from heat exchangers has been highlighted,
and its cause is supposed to be due to scattering of the inorganic
compounds.
As to usual aluminum or aluminum alloy-made heat exchangers for car
air conditioners, an aluminum or aluminum alloy coil material is
cut, punching molded and welding processed, and then assembled into
aluminum or aluminum alloy-made heat exchangers. Then, the
assembled heat exchangers are subjected, after a proper
pre-washing, to a chemical conversion treatment for giving
corrosion resistance such as chromic acid chromate treatment, and
then subjected to a hydrophilic treatment as above-mentioned.
The reason that the chemical conversion treatment for giving
corrosion resistance is carried out before the hydrophilic
treatment is that hydrophilic treatment, as above-mentioned, alone
cannot give corrosion resistance to aluminum or aluminum alloy-made
heat exchangers.
However, it is troublesome to carry out corrosion resistance and
hydrophilic treatments separately, and moreover, a washing step and
a draining step such as air blow generally become necessary after
the chemical conversion treatment, and therefore, steps further
increase and the equipment becomes larger and more complicated.
Further, as to chromic acid chromates and phosphoric acid chromates
generally used for chemical conversion treatments, hexavalent
chromium harmful to human bodies is contained in the treating
agents, and therefore, there is the possibility that they have a
bad influence on the environment and waste water treatment.
Various methods have been proposed for solving these problems. For
example, Japanese Published Unexamined Patent Application No.
318496/1988 discloses "a method for surface treating heat
exchangers which comprises giving hydrophilicity, corrosion
resistance, antibacterial properties and antifungal properties by
one surface treatment step" for omitting chemical conversion
treatment. However, constituents therefor are not explicitly
described even in examples as well as in claims, and are poor in
specificity.
Japanese Published Unexamined Patent Application No. 171684/1988
discloses "a method for applying an aqueous agent for hydrophilic
treatment, capable of giving corrosion resistance". Therein, film
giving corrosion resistance and hydrophilicity is formed, on
aluminum or aluminum alloy materials, by a resin synthesized from
particular monomers. However, hydrophilicity given by this method
is not yet enough, and in many cases, the method is generally used
only for forming a substrate for hydrophilic films.
Further, Japanese Published Unexamined Patent Application No.
270977/1989 discloses "a method for hydrophilic treatment of
aluminum or aluminum alloy, which gives both good hydrophilicity
and good corrosion resistance". Therein, film giving corrosion
resistance and hydrophilicity is formed from a particular polymer
polymer P1, a polymer P2 having a particular functional group and a
crosslinking agent. However, hydrophilic film formed by this method
contains hexavalent chromium, which is environmentally
undesirable.
Thus, a composition for hydrophilicity-giving treatment, not
containing hexavalent chromium, which can form uniform film having
hydrophilicity persistent over a long period and good corrosion
resistance without substrate film, by directly applying it on the
surface of aluminum or aluminum alloy products such as aluminum or
aluminum alloy-made heat exchangers, has not yet been
developed.
DESCRIPTION OF THE INVENTION
Objects of the Invention
This invention has been made for solving the problems which the
above prior art has, and the object of the invention is to provide
a composition for hydrophilic treatment which can form films
showing excellent corrosion resistance over a long period, and,
over a long period, not forming odor and capable of sustaining
excellent hydrophilicity, without using any substrate film used
generally, by directly applying it on the surface of aluminum or
aluminum alloy products such as aluminum or aluminum alloy-made
heat exchangers, and a method for hydrophilic treatment using the
composition.
SUMMARY OF THE INVENTION
The present inventors intensely studied on means for solving the
above problems, and as a result, they found that these problems can
be solved by applying a composition for hydrophilic treatment,
which contains a polymer having a particular structure, a
water-soluble trivalent chromium compound, and a water-soluble
zirconium compound or a water-soluble titanium compound, onto the
surface of aluminum or aluminum alloy, and completed the
invention.
Namely, the invention relates to a composition for hydrophilic
treatment of aluminum or aluminum alloy which comprises
(P1) a water-soluble polymer obtained by homopolymerizing one of
monomers (I) represented by the general formula ##STR2##
wherein, R.sup.1 represents a hydrogen atom or a methyl group, and
R.sup.2 and R.sup.3 are the same or different, and each represent a
hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a benzyl
group or a hydroxyalkyl group having 2 or 3 carbon atoms,
obtained by copolymerizing two or more of monomers (I), obtained by
copolymerizing monomer(s) (I) with other monomer(s) (II)
copolymerizable with the monomer(s) (I) or salt(s) of the
monomer(s) (II) under such a condition that the rate of the
monomer(s) (I) in the total monomers is 40% by mol or more, or
obtained by subjecting the resultant homopolymer or copolymer to
conventional modification,
(A) a water-soluble trivalent chromium compound,
(B) a water-soluble zirconium compound or titanium compound,
and, if necessary, further water,
and wherein the mutual rate of P1, A and B is such that, based on
100 weight parts of the solid matter of P1, A is 0.01 to 70 weight
parts and B is 0.001 to 70 weight parts.
When the above composition for hydrophilic treatment of aluminum or
aluminum alloy further contains, in an amount of 1 to 400 weight
parts based on 100 weight parts of P1 in solid matter basis, (P2) a
water-soluble polymer obtained by homopolymerization of any of
monomers (III) having in the molecule a carboxyl group, a sulfonic
acid group, a phosphonic acid group, a primary amino group, a
secondary amino group, a tertiary amino group, a quaternary
ammonium group, a hydroxyl group, a glycidyl group or an amido
group, and being different from monomers (I), and salts of monomers
(III) or copolymerization of two or more of monomers (III) and
salts thereof, or obtained by copolymerization of monomer(s) (III)
or salt(s) thereof with nonioic monomer(s) copolymerizable with the
monomer(s) (III) or salt(s) thereof but having neither a hydroxyl
group, a glycidyl group nor an amido group, the water-soluble
polymer (P2) being such that the rate of the monomer(s) (III) or
salt(s) thereof in the total monomers is 40% by mol or more, the
hydrophilicity of the aluminum or the aluminum alloy can further be
enhanced.
Further, when the above composition for hydrophilic treatment of
aluminum or aluminum alloy further contains an antibacterial agent
having a decomposition temperature of 100.degree. C. or more,
rotting odor due to metabolites of microorganisms proliferating at
the fin gaps can be prevented.
The invention also relates to a method for hydrophilic treatment of
aluminum or aluminum alloy which comprises applying the above
composition for hydrophilic treatment of aluminum or aluminum alloy
onto the surface of the aluminum or aluminum alloy, and drying to
form hydrophilic film having a film thickness of 0.05 to 20
.mu.m.
DESCRIPTION OF PREFERRED EMBODIMENTS
The invention is detailedly described below.
The "composition and method for hydrophilic treatment of aluminum
or aluminum alloy" in the invention is assumed to mean a
composition and a method for treatment to make the surface of
aluminum or aluminum alloy hydrophilic.
The "monomer" in the invention is assumed to mean a monomer having
an ethylenical double bond and capable of polymerizing or
copolymerizing thereby.
The "water-soluble polymer" in the invention is assumed to include,
according to a custom of the art, both of a water-soluble polymer
itself as solid matter and a water-soluble polymer as an aqueous
solution, and when both are referred to separately, it is assumed
to add the word of "solid matter" or "aqueous solution".
As apparent from the above, water-soluble polymer can be an aqueous
solution of the water-soluble polymer obtained by homopolymerizing
or copolymerizing respective components and then, if necessary,
modifying the resultant homopolymer or copolymer, or can be the
solid matter of the water-soluble polymer obtained by mere
separation or purification and isolation. Namely, it causes no
inconvenience if a polymerization initiator used in preparation of
water-soluble polymers, and other additives usually used in
polymerization or modification are contained in the composition of
the invention, so long as the object of the invention is not
hindered thereby.
First, the composition for hydrophilic treatment of aluminum or
aluminum alloy is described.
As the water-soluble polymer designated P1, there can, first, be
mentioned a water-soluble polymer (P1-1) obtained by
homopolymerization of the monomer (I) or copolymerization of two or
more of monomers (I). In the case of such a copolymer, there is no
limitation on their mutual rate.
As monomers (I), there can be mentioned acrylamide, methacrylamide,
N-methylacrylamide, N,N-dimethylacrylamide, etc. Only for
convenience, acrylamide, methacrylamide, N-methylacrylamide and
N,N-dimethylacrylamide are hereinafter referred to, individually to
as a whole, as monomers (I').
As the water-soluble polymer designated P1, there can, also, be
mentioned a water-soluble monomer (P1-2) obtained by copolymerizing
monomer(s) (I) with monomer(s) (II) other than monomers (I) or
salt(s) of the monomer(s) (II), copolymerizable with the monomer(s)
(I), under such a condition that the rate of the monomer(s) (I) in
the total monomers is 40% by mol or more.
There is no particular limitation on the monomer(s) (I) to be
copolymerized with monomer(s) (II), so long as they are monomer(s)
(I), but it is preferred that they are monomer(s) (I'). Monomers
(I) can be used alone or in combination of two or more of them.
As monomers (II), there can be mentioned nonionic monomers (II-1),
cationic monomers (II-2) and anionic monomers (II-3) different from
monomers (I).
Monomers (II) can be used alone or in combination of two or more of
them.
As nonionic monomers (II-1), there can, for example, be mentioned
2-hydroxyalkyl (C=2, 3) (meth)acrylate, diacetoneacrylamide,
N-methylolacrylamide, acryloylmorpholine, acrylonitrile, alkyl
(C=1.about.6) (meth)acrylate, styrene, vinyl acetate, etc.
As cationic monomers (II-2), there can, for example, be mentioned
ones represented by the following general formula: ##STR3##
Therein, R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.1 represents a group giving cationic properties, and, for
example, include the following ones. ##STR4##
wherein, R.sup.a and R.sup.b are the same or different, and each
represent a hydrogen atom, an alkyl group (C=1.about.6,
particularly 1, 2), a hydroxyalkyl group (the alkyl has
C=1.about.6, particularly 1, 2), a phenyl group or a benzyl group,
and y represents an integer of 1.about.3).
As the salts of cationic monomers (II-2), there can be mentioned
salts with inorganic acids such as hydrochloric acid and sulfuric
acid and salts with organic acids such as acetic acid and citric
acid, and further, adducts of alkyl halides (methyl chloride, ethyl
chloride, etc.), alkyl sulfates (methyl sulfate, ethyl sulfate,
etc.) or the like, and quaternary ammonium salts obtained by
reaction with dimethyldiallyl ammonium salts (chlorides, sulfates,
etc.) or with chloromethylstyrene and a tertiary amine
(triethylamine, etc.), etc.
As anionic monomers (II-3), there can, for example, be mentioned
ones represented by the following general formula, other
unsaturated carboxylic acids such as maleic anhydride and itaconic
acid, etc. ##STR5##
Therein, R.sup.1 represents a hydrogen atom or a methyl group, and
M.sup.2 represents a group giving anionic properties, and, for
example, include the following ones. ##STR6##
As the salts of anionic monomers (II-3), there can be mentioned
sodium salts, potassium salts, ammonium salts, salts with amines
such as triethylamine, etc.
The compositions of the water-soluble polymers (P1-2) can thus be
represented as follows.
Nonionic polymers represented by the general formula
(wherein, n.gtoreq.40, p=1.about.60, n+p=100),
Cationic polymers represented by the general formula
(wherein, n.gtoreq.40, p=0.about.59, q=1.about.60, n+p+q=100),
Anionic polymers represented by the general formula
(wherein, n.gtoreq.40, p=0.about.59, r=1.about.60, n+p+r=100),
or
Amphoteric polymers represented by the general formula
(wherein, n.gtoreq.40, 0.ltoreq.p<30, q=1.about.59,
r=1.about.59, n+p+q+r=100).
As water-soluble polymers represented by P1, there can also be
mentioned water-soluble polymers (P1-3) obtained by subjecting the
thus obtained homopolymers or copolymers, namely water-soluble
polymers (P1-1) or (P1-2) to conventional modifications.
As examples of the conventional modifications, there can be
mentioned
1) Conversion of amido groups to carboxyl groups through
hydrolysis
2) Conversion of amido groups to amino groups through Hofmann
rearrangement
3) Conversion of amido groups to --CONH--CH.sub.2
--N(R.sup.4)(R.sup.5) through Mannich reaction using
HN(R.sup.4)(R.sup.5) and formaldehyde
(wherein, R.sup.4 and R.sup.5 are the same or different, and each
represent an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl
group having 2 or 3 carbon atoms or a benzyl group)
4) Introduction of --CONH--R.sup.6 --NH.sub.2 through reaction of
the side chain ester groups with alkylenediamine (H.sub.2
N--R.sup.6 --NH.sub.2)
(wherein, R.sup.6 represents an alkylene group having 2 to 6 carbon
atoms)
5) Conversion of (substituted) amino groups obtained by the
reactions of 2) to 4) to quaternary ammonium through alkylation,
etc.
There is no particular limitation about the process for the
homopolymerization or copolymerization for obtaining the
water-soluble polymer (Pi) of the invention, and the process can be
carried out according to conventional processes. For example, one
or two or more monomers are dissolved or suspended in water, and
polymerization is carried out at a reaction temperature of 50 to
100.degree. C. using potassium persulfate or the like as a
polymerization initiator and sodium thiosulfate or the like as a
polymerization accelerator. For adjustment of polymerization
degree, there can be used secondary alcohols, mercaptosuccinic
acid, etc. as chain transfer agents.
Further, the modifications (hydrolysis, Hofmann rearrangement,
Mannich reaction, conversion to quaternary ammonium compounds,
etc.) of the thus obtained homopolymers or copolymers in the case
of necessity can be carried out according to conventional
processes.
It is suitable, for securing the durability of the film, that the
molecular weight of the obtained water-soluble polymer (P1) is
5,000 or more according to gel permeation chromatography (GPC)
using a polyacrylic acid ester as a standard substance. The
molecular weight is preferably 5,000 to 300,000, more preferably
10,000 to 100,000.
As the water-soluble trivalent chromium compounds (A), there is no
particular limitation, and there can, for example, be mentioned
chromium sulfate, chromium nitrate, chromium fluoride, chromium
acetate, chromium chloride, chromium biphosphate, etc.
In general, it is necessary that the use amount of the
water-soluble trivalent chromium compound (A) is 0.01 to 70 weight
parts per 100 weight parts of the solid matter of the water-soluble
polymer (P1), and the use amount is referably 0.1 to 50 weight
parts, more preferably 1 to 50 weight parts, still more preferably
5 to 40 weight parts. When the compounding amount is less than 0.01
weight part, the corrosion resistance is insufficient, and when it
is more than 70 weight parts, there is the possibility that odor is
generated.
As the water-soluble zirconium compounds or titanium compounds (B),
there is no particular limitation, and there can, for example, be
mentioned zirconium acetate, zirconium nitrate, zirconium chloride,
hexafluorozirconic acid and its salts (Na salt, K salt, etc.),
zirconium sulfate, zirconium carbonate, hexafluorotitanic acid and
its salts (Na salt, K salt, etc.), titanium sulfate, etc.
In general, it is necessary that the use amount of the
water-soluble zirconium compounds or titanium compounds (B) is
0.001 to 70 weight parts per 100 weight parts of the solid matter
of the water-soluble polymer (P1), and the use amount is preferably
0.1 to 50 weight parts, more preferably 0.5 to 50 weight parts,
still more preferably 1 to 40 weight parts. When the compounding
amount is less than 0.001 weight part, the corrosion resistance is
insufficient, and when it is more than 70 weight parts, there is
the possibility that odor is generated.
As to the composition of the invention for hydrophilic treatment of
aluminum or aluminum alloy, as stated above, the object of the
invention can be accomplished so long as it comprises the above
components P1, A and B, and, if necessary, further water. However,
when the composition further contains, in an amount of 1 to 400
weight parts based on 100 weight parts of P1 in solid matter basis,
(P2) a water-soluble polymer obtained by homopolymerization of any
of monomers (III) having in the molecule a carboxyl group, a
sulfonic acid group, a phosphonic acid group, a primary amino
group, a secondary amino group, a tertiary amino group, a
quaternary ammonium group, a hydroxyl group, a glycidyl group or an
amido group, and being different from monomers (I), and salts of
monomers (III), or copolymerization of two or more of monomers
(III) and salts thereof, or obtained by copolymerization of
monomer(s) (III) or salt(s) thereof with nonioic monomer(s)
copolymerizable with the monomer(s) (III) or salt(s) thereof but
having neither a hydroxyl group, a glycidyl group nor an amido
group, the water-soluble polymer (P2) being such that the rate of
the monomer(s) (III) or salt(s) thereof in the total monomers is
40% by mol or more, the hydrophilicity of the obtained film can
further be enhanced.
In the above, as the monomers (III) having in the molecule a
carboxyl group, a sulfonic acid group or a phosphonic acid group
and salts thereof, there can be used anionic monomers and salts
thereof stated in the description of the above P1 can be used.
Further in the above, as the monomers (III) having in the molecule
a primary amino group, a secondary amino group, a tertiary amino
group or a quaternary ammonium group and salts thereof, there can
be used cationic monomers and salts thereof stated in the
description of the above P1 can be used. Further in the above, as
the monomers (III) having in the molecule a hydroxyl group, a
glycidyl group or an amido group, and being different from monomers
(I), there can be used 2-hydroxyalkyl (C=2, 3)(meth)acrylate,
N-methylol(meth)acrylamide, diacetoneacrylamide, etc.
In the above, as the nonioic monomers copolymerizable with the
monomers (III) but having neither a hydroxyl group, a glycidyl
group nor an amido group, there is no particular limitation, but
there can, for example, be mentioned styrene, alkyl (C=1 to 8)
(meth)acrylate, vinyl acetate, etc.
The process of the above homopolymerization or copolymerization for
obtaining the water-soluble polymer (P2) used in the invention can
be the same as in the case of the water-soluble polymer (P1).
It is suitable, for securing the hydrophilicity of the film, that
the molecular weight of the obtained water-soluble polymer (P2) is
1,000 or more according to gel permeation chromatography (GPC)
using a polyacrylic acid ester as a standard substance. The
molecular weight is preferably 1,000 to 500,000, more preferably
5,000 to 200,000.
When the water-soluble polymer (P2) is used, its use amount in the
composition of the invention, based on solid matter, is suitably 1
to 400 weight parts, preferably 5 to 300 weight parts per 100
weight parts of P1.
Further, rotting odor due to metabolites of microorganisms
proliferating at the fin gaps can be inhibited by incorporating an
antibacterial agent having a decomposition temperature of
100.degree. C. or more into the composition for hydrophilic
treatment of the invention.
As the antibacterial agent having a decomposition temperature of
100.degree. C. or more, there is no particular limitation, but
there can, for example, be mentioned
5-chloro-2-methyl-4-isothiazolin-3-one,
2-methyl-4-isothiazolin-3-one,
2-(4-thiocyanomethylthio)benzothiazole,
2,2-dibromo-3-nitrilopropionamide, sodium ethylenebis
(dithiocarbamate), sodium 2-pyridinethiol-1-oxide,
2,2'-dithiobis(pyridine-1-oxide),
2,4,5,6-tetrachloroisophthalonitrile,
2-methylcarbonylaminobenzimidazole, zinc 2-pyridinethiol-1-oxide,
2-(4-thiazolyl)-benzimidazole, p-chloro-m-xylenol,
1,2-benzisothiazolin-3-one, 2-bromo-2-nitropropane-1,3-diol, barium
metaborate, 2-n-octyl-4-isothiazolin-3-one,
bis(1-hydroxy-2-pyridinethionato) zinc, zeolite compounds having Ag
or Cu, etc.
When the antibacterial agent is used, as to its use amount in the
composition of the invention, it is sufficient if it is an amount
enough to exert antibacterial effect, but, usually, the use amount
is suitably 0.01 to 50 weight parts, preferably 0.1 to 50 weight
parts per 100 weight parts of P1 solid matter.
Rust inhibiors, leveling agents, fillers, colorants, surfactants,
antifoaming agents, etc. can be added, in such a range that the
effect of the invention and film performance are not spoiled, into
the composition for hydrophilic treatment of aluminum or aluminum
alloy of the invention.
The solid matter concentration of the composition for hydrophilic
treatment of aluminum or aluminum alloy of the invention can be
such a solid matter concentration that the thickness of film formed
by applying the composition once onto the surface of aluminum or
aluminum alloy and drying it becomes 0.05 to 20 .mu.m, particularly
0.1 to 5 .mu.m.
Next, description is made on the method for hydrophilic treatment
of aluminum or aluminum alloy of the invention, using the
composition for hydrophilic treatment.
Matter onto which the hydrophilic treatment is to be made is
aluminum or aluminum alloy, more detailedly aluminum or aluminum
alloy-made materials or products. As the aluminum alloy, there is
no particular limitation, but there can be exemplified aluminum
alloys which are alloys of aluminum with manganese, silicon,
magnesium or the like and wherein the aluminum content is 80% by
weight or more, and, specifically, there can be mentioned JIS 2024,
JIS 3004, JIS 5052, etc. There can be mentioned sheet materials,
tubular materials, bar materials, fin materials used for heat
exchangers, etc. as the aluminum or aluminum alloy-made materials,
and heat exchangers, refrigerators, etc. as the aluminum or
aluminum alloy-made products.
The composition for hydrophilic treatment of the invention is used
particularly suitably for hydrophilic treatment of aluminum or
aluminum alloy-made heat exchangers using post-coating
treatment.
In application of the composition of the invention, prior thereto,
degreasing, washing with water and drying are usually carried out
by conventional methods.
The composition of the invention can be applied onto the surface of
aluminum or aluminum alloy by a usual application method, for
example by immersion, roll coating, flow coating or the like.
After the application of the composition of the invention, drying
is carried out. Methods for the drying are not particularly
limited, but, usually, it is suitable to carry out the drying by
hot-air drying at 80 to 300.degree. C., particularly 100 to
250.degree. C.
It is necessary that the film thickness after the drying is 0.05 to
20 .mu.m, and, preferably, it is 0.1 to 5 .mu.m. In less than 0.05
.mu.m, it is difficult to give sufficient hydrophilicity to the
matter to be subjected to the hydrophilic treatment, and in more
than 20 .mu.m, there is the possibility that the heat conductivity
of the matter is lowered.
Film obtained using the composition for hydrophilic treatment of
aluminum or aluminum alloy of the invention does not generate odor
and maintains excellent corrosion resistance and hydrophilicity,
over a long period. Further, by thus giving corrosion resistance to
the hydrophilic film, it became possible to omit chemical
conversion treatment which has generally been carried out.
The mechanism of the corrosion inhibition effect of the hydrophilic
film by the composition of the invention is not entirely made
clear, but is thought to be as follows.
Although it is known that the water-soluble polymer (P1) and the
water-soluble chromium (III) compound form a film having reticular
structure, it is considered that the film of reticular structure is
made stronger by the water-soluble zirconium compound or titanium
compound (B), and thereby the progress of corrosion is hindered.
Further, it is considered that, thereby, excellent corrosion
resistance over a long period only by this hydrophilic film is made
possible, and excellent hydrophilicity and deodorant properties can
be maintained over a long period. It is considered that it is
because the formed film does not contain odor components and the
film prevents the generation of odor components due to corrosion,
etc., that odor is not generated over a long period.
EXAMPLES
The invention is further specifically described below by examples,
but these are mere exemplifications and do not imply any limitation
of the invention at all
Example 1
An aluminum (JIS 3003)-made heat exchanger was immersed for 50
seconds in 30 g/L aqueous solution of a weakly alkaline degreasing
agent (Fine Cleaner 315, made by Nihon Parkerizing Co., Ltd.) to
remove contaminants such as oily matter on the surface, and washed
with city water for 30 seconds. The heat exchanger was immersed in
a composition for hydrophilic treatment comprising 100 weight parts
of polyacrylamide solid matter (molecular weight: about 50,000), 10
weight parts of chromium biphosphate, 10 weight parts of
hexafluorotitanic acid and 5,000 weight parts of water at
25.degree. C. for 30 seconds, drained by air blow, and heat dried
for 30 minutes in an oven with internal air circulation adjusted to
140.degree. C. to form hydrophilic film. The thickness of this film
was measured using the surface carbon-measuring apparatus of LECO
Co. (USA).
Example 2
The procedure of Example 1 was repeated to form hydrophlic film,
except that a composition for hydrophilic treatment comprising 100
weight parts of polyacrylamide solid matter (molecular weight:
about 50,000), 30 weight parts of chromium biphosphate, 30 weight
parts of hexafluorozirconic acid and 5,000 weight parts of water
was used in place of the composition for hydrophilic treatment of
Example 1.
Example 3
The procedure of Example 1 was repeated to form hydrophlic film,
except that a composition for hydrophilic treatment comprising 100
weight parts of polyacrylamide solid matter (molecular weight:
about 30,000), 10 weight parts of chromium fluoride, 10 weight
parts of hexafluorozirconic acid and 5,000 weight parts of water
was used in place of the composition for hydrophilic treatment of
Example 1.
Example 4
The procedure of Example 1 was repeated to form hydrophlic film,
except that a composition for hydrophilic treatment comprising 100
weight parts of the copolymer solid matter (molecular weight: about
40,000) between acrylamide (90% by mol) and sodium
2-acrylamido-2-methylpropanesulfonate (10% by mol), 50 weight parts
of chromium fluoride, 10 weight parts of hexafluorozirconic acid
and 5,000 weight parts of water was used in place of the
composition for hydrophilic treatment of Example 1.
Example 5
The procedure of Example 1 was repeated to form hydrophilic film,
except that a composition for hydrophilic treatment comprising 100
weight parts of the sodium salt solid matter (molecular weight:
about 70,000) of the copolymer between acrylamide and acrylic acid
in a mol ratio of 80:20, 10 weight parts of chromium sulfate, 1
weight part of titanium sulfate and 5,000 weight parts of water was
used in place of the composition for hydrophilic treatment of
Example 1.
Example 6
The procedure of Example 1 was repeated to form hydrophlic film,
except that a composition for hydrophilic treatment comprising the
composition for hydrophilic treatment of Example 1 having added
thereinto 20 weight parts of poly (sodium
2-acrylamido-2-methylpropanesulfonate) was used in place of the
composition for hydrophilic treatment of Example 1.
Comparative Example 1
The procedure of Example 1 was repeated to form hydrophlic film,
except that the same composition for hydrophilic treatment as in
Example 1 except for not containing the polyacrylamide was used in
place of the composition for hydrophilic treatment of Example
1.
Comparative Example 2
The procedure of Example 1 was repeated to form hydrophlic film,
except that the same composition for hydrophilic treatment as in
Example 2 except for not containing chromium biphosphate was used
in place of the composition for hydrophilic treatment of Example
1.
Comparative Example 3
The procedure of Example 1 was repeated to form hydrophlic film,
except that the same composition for hydrophilic treatment as in
Example 3 except for not containing hexafluorozirconic acid was
used in place of the composition for hydrophilic treatment of
Example 1.
Comparative Example 4
The procedure of Example 1 was repeated to form hydrophlic film,
except that the same composition for hydrophilic treatment as in
Example 3 except that 200 weight parts of hexafluorozirconic acid
was used in place of 10 weight parts of hexafluorozirconic acid was
used in place of the composition for hydrophilic treatment of
Example 1.
Evaluation Tests
The heat exchangers having provided film thereon, prepared in
Examples 1 to 5 and Comparative examples 1 to 4, were evaluated
according to the following methods.
<Test methods>
(1) Initial hydrophilicity
The contact angle against water of the fin part of each heat
exchanger was measured using a FACE contact angle-type CA-P type
contact angle-measuring apparatus (made by Kyowa Kaimen Kagaku Co.,
Ltd.).
(2) Hydrophilicity after endurance
The contact angle against water of the fin part after 72 hours
immersion in running water at room temperature was measured using
the above type contact angle-measuring apparatus.
(3) Corrosion resistance
In the corrosion resistance test based on the salt spray test
method JIS Z-2371, the rusted area after 72 hours exposure was
evaluated from appearance. The evaluation criterion is as
follows.
.circleincircle. No discoloration was observed
.largecircle. Rust is generated less than 10%
.quadrature. Rust is generated 10% or more but less than 2%
.DELTA. Rust is generated 25% or more but less than 50%
X Rust is generated 50% or more
(4) Deodorant properties
Odor after 72 hours immersion in running water (deionized water:
0.5 L/min) was evaluated in 5 stages.
The evaluation criterion is as follows.
.circleincircle. There is no odor
.largecircle. There is slight odor
.quadrature. There is a little odor
.DELTA. There is distinct odor
X There is strong odor
On the aluminum-made heat exchangers having hydrophlic film of
Examples 1 to 5 and Comparative examples 1 to 4, the compositions
of the compositions for hydrophilic treatment and the thickness of
the films, and the results of evaluation according to the
evaluation methods are shown together in Table 1.
As apparent from Table 1, in the aluminum-made heat exchangers
treated with the compositions for hydrophilic treatment of the
invention of Examples 1 to 5, the films have, even after the
durability test, excellent hydrophilicity, corrosion resistance and
deodorant properties. On the other hand, in the aluminum-made heat
exchangers treated with the compositions for hydrophilic treatment
lacking in even one of the components according to claim 1 of
Comparative examples 1 to 3, at least one of the corrosion
resistance, hydrophilicity and deodorant properties of the films
was insufficient. Further, in Comparative example 4 where
hexafluorozirconic acid was compounded in an amount of as excess as
200 weight parts, deodorant properties were insufficient.
TABLE 1 Results of evaluation of the compositions for hydrophilic
treatment Composition of the composition for hydrophilic treatment
Contact angle (.degree.) (The numbers in parentheses are weight
parts) Film After Chromium Zirconium/titanium thickness running
Corrosion Deodorant Polymer P1 compound A compound B (.mu.m)
Initial water resistance properties Example 1 Polyacrylamide
Chromium Hexafluorotitanic 0.5 8 21 .circleincircle.
.circleincircle. (100) biphoshate (10) acid (10) 2 Polyacrylamide
Chromium Hexafluorozirconic 0.5 11 25 .circleincircle.
.circleincircle. (100) biphoshate (30) acid (30) 3 Polyacrylamide
Chromium Hexafluorozirconic 1.0 7 19 .circleincircle.
.circleincircle. (100) fluoride (10) acid (10) 4 Copolymer 1*.sup.1
Chromium Hexafluorozirconic 1.0 10 18 .largecircle.
.circleincircle. (100) fluoride (50) acid (10) 5 Copolymer 2*.sup.2
Chromium Titanium sulfate (1) 2.0 12 21 .largecircle.
.circleincircle. (100) sulfate (10) 6 Polymer mixture *.sup.3
Chromium Hexafluorotitanic 1.0 11 15 .largecircle. .circleincircle.
biphosphate (10) acid (10) Comparative 1 -- Chromium
Hexafluorotitanic 0.1 45 60 .DELTA. X Example biphosphate (10) acid
(10) 2 Polyacrylamide -- Hexafluorozirconic 1.0 21 53 X .DELTA.
(100) acid (30) 3 Polyacrylamide Chromium -- 1.0 10 24 .DELTA.
.largecircle. (100) fluoride (10) 4 Polyacrylamide Chromium
Hexafluorozirconic 2.0 11 22 .circleincircle. X (100) fluoride (10)
acid (200) *.sup.1 Copolymer between acrylamide (90 mol %) and
sodium 2-acrylamido-2-methylpropanesulfonate (10 mol %) *.sup.2
Sodium salt of copolymer between acrylamide and acrylic acid in
80:20 (mol ratio) *.sup.3 Polymer P1:polyacrylamide (100), polymer
P2:poly(sodium 2-acrylamido-2-methylpropanesulfonate (20)
Hydrophlic film obtained by treating aluminum or aluminum alloy
with the composition for hydrophilic treatment of the invention
shows, even after the durability test, excellent hydrophilicity,
corrosion resistance and deodorant properties, although it is
single-layer film.
* * * * *